Corrugated drainage tubes

ABSTRACT

A FLEXIBLE CORRUGATED DRAINAGE TUBE HAVING ALTERNATING ANNULAR PEAKS AND VALLEYS AND A PLURALITY OF OPENINGS ARRANGED TRANSVERSELY TO THE LONGITUDINAL AXIS OF THE TUBE. FILTER MEDIA COVERS THE SLOTTED OPENINGS SO THAT LIQUID DRAINING THROUGH THE OPENINGS INTO THE INTERIOR OF THE TUBE INITIALLY PASSES THROUGH THE FILTER MEDIA.

March 2, 1971 M. E, slxT 3,566,607

I CORRUGATED DRAINAGE TUBES Filed Feb. 14, 1968 2 Sheets-Sheet 1 March2, 1 971 M. E. SIXT 3,566,607

CORRUGATED DRAINAGE TUBES 2 Sheets-Sheet 2 Filed Feb. 14, 1968 fig-L9.

United States Patent US. CI. 61-11 2 Claims ABSTRACT OF THE DISCLOSURE Aflexible corrugated drainage tube having alternating annular peaks andvalleys and a plurality of openings arranged transversely to thelongitudinal axis of the tube. Filter media covers the slotted openingsso that liquid draining through the openings into the interior of thetube initially passes through the filter media.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is acontinuation-in-part of application Ser. No. 666,051, filed Aug. 24,1967 and now abandoned.

BACKGROUND OF THE INVENTION The present invention relates to drainagetubes, and more particularly to flexible corrugated drainage tubes thatfilter incoming liquids.

In the past, land improvement through subsurface drainage systems was anexpensive and time-consuming operation. The red clay tile commonly usedfor this purpose required the manual piecing together of relativelyshort lengths to construct the desired system. Misalignment of the tilepieces was and still is, a constant problem and extreme care is requiredwhen the drainage systems of tiles is covered with earth in order toavoid breakage of the tile material. Often, in soils having a high siltor colloidal count the subsurface drainage networks become cloggedthereby rendering them unsuitable for their intended purpose. Hence, theindustry has long sought a drainage system which avoids the above noteddisadvantages.

Accordingly, it is an object of the present invention to provide simple,inexpensive and easy-to-install drainage tubes for use in constructingsubsurface drainage networks that function in a highly beneficial andtroublefree manner.

SUMMARY OF THE INVENTION In accordance with the present invention, aflexible corrugated drainage tube having alternating annular peaks andvalleys is provided with a plurality of slotted openings arrangedtransversely to the longitudinal axis of the tube. Filter materialcovers the slotted openings so that liquid draining through the openingsinto the interior of the tube initially passes through the filtermaterial.

The slotted openings may be arranged in selected annular valleys of thetube with the filter material disposed in the selected annular valleys.Moreover, the filter material can be secured to the drainage tube byadhesive or by positioning a portion of the filter material through theslotted opening it covers into the interior of the tube. Alternatively,apertures may be provided adjacent the ends of each slotted opening andportions of the filter material covering that opening forced through theapertures into the interior of the tube to anchor the filter material.

The filter material may comprise a plurality of narrow strips, one stripfor each selected annular valley. Each strip fills the annular valley inwhich it is located and completely surrounds the drainage tube.Moreover, the filter material can take the form of a unitary sheath that3,566,607 Patented Mar. 2, 1971 "ice completely envelopes the drainagetube with portions of the sheath extending into the annular valleys ofthe tube in which the slotted openings are located.

Another type of drainage tube has a spiral corrugation with slottedopenings in the corrugation. An endless elongate strip of filtermaterial is disposed in the spiral corrugation so that liquid draininginto the tube through the slotted openings initially passes through thefilter material.

BRIEF DESCRIPTION OF THE DRAWING Novel features and advantages of thepresent invention in addition to those mentioned above will becomeapparent to one skilled in the art from a reading of the followingdetailed description in conjunction with the accompanying drawingwherein similar reference characters refer to similar parts and inwhich:

FIG. 1 is a side elevational view of a corrugated drainage tubeaccording to the present invention with portions broken away to showdetail;

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a sectional view similar to FIG. 2 illustrating anotherembodiment of the present invention;

FIG. 4 is a sectional view similar to FIG. 2 illustrating anotherembodiment of the invention;

FIG. 5 is a sectional view similar to FIG. 2 illustrating still anotherembodiment of the present invention with the filter material shown inelevation;

FIG. 6 is a side elevational view of another corrugated drainage tubeaccording to the present invention with portions broken away to showdetail;

FIG. 7 is a sectional view taken along line 77 of FIG. 6 with the filtermaterial shown in elevation;

FIG. 8 is a side elevational view of still another corrugated drainagetube according to the present invention with portions broken away toshow detail;

FIG. 9 is a side elevational view of another corrugated drainage tubeaccording to the present invention with portions broken away to showdetail; and

FIG. 10 is a sectional view taken along line 1010 of FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION Referring in more particularity tothe drawing, FIG. 1 illustrates a portion of a flexible corrugateddrainage tube 10. In use, a plurality of drainage tubes, such as 10, areinterconnected with proper fittings and connectors to construct asubsurface drainage network or system. For the most part, the drainagesystem usually comprises a series of main lines as well as a pluralityof lateral lines or branches that empty into the mains. The length ofthe drainage tubes is only limited by the convenience in handling andshipping them. The drainage system is arranged below the surface of afield for example by digging slit trenches and then positioning thedrainage tubes in the trenches. Finally, earth is filled in around thetubes to complete the istallation of the subsurface drainage systern.

Corrugated drainage tubes, such as 10, are preferably fabricated ofdurable, high-strength polyethylene although other materials aresuitable. Extruding techniques may be employed to initially shape thetubing by forcing molten plastic material through an annular orifice, asis well known. The corrugations are formed by a reshaping operation.

The corrugated drainage tube 10 comprises a body port-ion 12 having aseries of alternating annular peaks 14 and valleys 16. Selected annularvalleys are provided with drainage slots or openings 18 arrangedtransversely to the longitudinal axis of the tube so that liquid canpass into the tube and drain away into a main, irrigation ditch,

or waterway, for example. As shown in FIGS. '1 and 2, a drainage slot 18is provided in every annular valley 16 of the corrugated drainage tube10. The width of the slots is about A of an inch and the length is suchthat the combined open area provided by all of :the slots in the tube ispreferably between about one-half and one percent of the longitudinalsurface area of the tube. This percentage of slotted open area to thelongitudinal surface area of the tube (functions exceptionally well toprovide proper drainage when installed. The slotted openings 18 providethe necessary fluid inlet area without sacrificing tube strength.Compared to perforations the slots are few in number, however, the widthis such that heavy soils do not enter into the tube during the drainingoperation.

Other slotted opening arrangements can also be utilized to provide thenecessary fluid inlet area. Although a longitudinal path of slottedopenings is shown in FIG. 1 with one slotted opening in each annularvalley, the slotted openings can be arranged three in every fourthannular valley or two in every other annular valley. Numerouscombinations are available within the scope of the present invention.

As shown in FIGS. 1 and 2, filter material 20 covers the slottedopenings 18. For purposes of illustration, one of the annular valleys ofthe tube illustrated in FIG. 1 is not covered by filter material, itbeing understood that in the finished product filter material isdisposed over the slotted opening in that valley. Each element of filtermaterial -20 is preferably preformed and has a length somewhat longerthan the length of the slotted opening it covers. The width of eachfilter element is approximately the same as the distance betweenadjacent peak portions .14 of the drainage tube 10.

Ester type polyurethane foam is a highly satisfactory filter materialfor use in fabricating tubing according to the present invention. Unlikeordinary urethane foams which are composed of strands connected by thinmembrane-like windows, the ester type polyurethane cfoam, of the typeproduced by Scott Paper Company, for example, has a three dimensionalstructure of skeletal strands alone which gives this foam uniquefiltering characteristics. Other filter materials are also suitable inconjunction with the corrugated drainage tubing of the presentinvention. Fiber glass and other synthetic fibers can be secured to thedrainage tube over the slotted openings 18 to provide the filterconstruction.

In FIG. 1, the individual strips of filter material are fabricated fromopen-celled polyurethane foam. Each strip of filter material ispreformed to a desired shape and is anchored by adhesive in one of theannular valleys over the slotted opening. The adhesive is preferablyapplied to opposite sides of the filter strip so that the securing takesplace between the side walls defining the annular valleys rather than atthe bottom of the valleys where the slotted openings are located. Byutilizing this expedient, the adhesive material does not cont-act thetube in the vicinity of the slotted openings thereby preventinginadvertent clogging of the openings through a buildup of adhesive atthe openings. Alternatively, the filter material can be manufactured orfoamed in place on the tubing after the slots are made.

FIG. 3 illustrates another embodiment of the present invention whereinthe slotted openings in a corrugated drainage tube are covered withfilter material by mechanically anchoring the material directly over theslotted openings. In this regard, the corrugated drainage tube includesapertures 22, one located at each end of each slotted opening. The endportions of each filter strip are compressed slightly and stuifedthrough the apertures 22 so that a portion 24 at each end of the filterstrip is located inside the drainage tube. Once this portion clears theaperture it springs back to its original shape whereby the filter stripis positively secured to the tube in covering relationship over theslotted opening. Alternatively, the

4 apertures 22 may be produced at the same time the filter material isforced therethrough.

FIG. 4 is a cross-sectional view similar to FIGS. 2 and 3, illustratinganother method for securing the filter material to the corrugateddrainage tube '10. In this instance, the central portion 26 of eachfilter strip is stufiFed through the slotted opening over which it isdisposed. As in the case of the embodiment of the invention shown inFIG. 3, once the central portion 26 of the filter material '20 clearsthe slotted opening 18 it springs back to its original shape which isconsiderably larger than the width of slot-ted opening it covers. Thisparticular orientation of filter material and tubing provides asatisfactory arrangement for securing the filter to the tubing over eachslotted opening.

Another form of the present invention is shown in FIG. 5 whereinselected annular valleys of a corrugated drainage tube 30 are providedwith a pair of slotted openings 32. Filter material 34 in the form of anarrow elongate strip completely surrounds each annular valley in whichthe slotted openings are located to thereby cover the slotted openings.Hence, liquid draining into the interior of the tube initially passesthrough the filter material 34. Each strip of filter material may beannular in configuration and simply snapped in place around the tube, orit can be a double ended piece in which case the ends are simply securedtogether by adhesive after it is positioned in one of the selectedannular valleys.

FIGS. 6 and 7 illustrate another embodiment of the present inventionwherein a flexible corrugated drainage tube has alternating annularpeaks 42 and valleys 44. Each of the valleys include three equallyspaced apart slotted openings 46. Filter material 48 in the form of aunitary sheath completely envelopes the corrugated drainage tube 40thereby covering the slotted openings 46 so that liquid draining throughthe openings into the interior of the tube initially passes through thefilter material. Portions 50 of the filter material 48 extend into theannular valleys 44 so that for a given exterior dimension of the filtersheath a maximum amount of filter material is disposed in the path ofthe incoming liquid.

FIG. 8 illustrates a drainage tube having a spiral corrugation 62 withspaced apart slotted openings 64 in the corrugation. An endless elongatestrip of filter material 66 is disposed in the spiral corrugation incovering relationship over the slotted openings. A machine similar to atoroidal core winder or tire wrapping machine can b utilized to wind orwrap the filter material around the tube. In operation, liquid drainingthrough the slotted openings into the interior of the tube initiallypasses through the filter material 66.

FIGS. 9 and 10 illustrate another embodiment of the present inventioncomprising a flexible corrugated drainage tube 70 having alternatingannular peaks 72 and valleys 74. The valleys are defined in part byannular side walls 76, 78 which serve to interconnect adjacent peaks andvalleys of the tube. As shown in FIG. 9, one of the side walls of eachvalley includes a pair of bulging portions 80 which extend into thevalley. The tip or end 82 of each bulge 80 is open to provide a slottedopening 84. The bulging portions 80 are integral with the tube, and thetube with its bulging portions can be produced by extrusion and suctionmolding techniques, for example. A downstream cutting operation may beused to sever the closed tip of each bulging portion to thereby providethe slotted openings 84. Alternatively, the molding equipment utilizedto manufacture the tube can be provided with suitable retractable coresso the ends of the bulging portions are open thereby eliminating thedownstream severing operation.

The bulging portions 84 can be located, one or two on each side wall 76,78 or any other desired combination. Moreover, the slotted openings 84can be dimensioned to provide the desired inlet open area.

Filter material 86 of the types described above covers the slottedopenings 84 to filter incoming liquids. Al-

though the filter material can be anchored in place by utilizing theabove described expedients, it is preferably secured in place by simplystufiing it into the annular valleys in the vicinity of the slottedopenings 84. The bulging portions 80 function to hold the filtermaterial in place by compressing the central portion of the filteropposite the bulges.

Once the tubing of the present invention is installed below the surfaceof a field, for example, the filter material functions as an ordinaryfilter, and additionally, as a surge mitigator. Thus, the filtermaterial reduced the velocity of the incoming water so that asignificant portion of the colloidal particles in the water precipitateout naturally. A layer of natural filter then begins to buildup aroundthe tubing to thereby progressively produce a more effective filter orsurge mitigator.

What is claimed is:

1. A flexible corrugated drainage tube having alternating flat annularpeaks and fiat annular valleys with walls interconnecting the fiat peaksand valleys, a plurality of slotted openings in the tube for providingcommunication between the interior and exterior of the tube so thatliquid can drain through the slotted openings into the interior of thetube, and filter material completely occupying the open space defined bythe fiat peaks and valleys and the interconnecting walls in the area ofthe slotted openings whereby liquid draining through the slottedopenings into the interior of the tube initially passes through thefilter material, and apertures in the tube adjacent the ends of eachslotted opening, portions of the filter material extending through theapertures into the interior of the tube to secure the filter material tothe tube.

2. A flexible corrugated drainage tube having alternating flat annularpeaks and flat annular valleys with walls interconnecting the fiat peaksand valleys, a plurality of slotted openings in the tube for providingcommunication between the interior and exterior of the tube so thatliquid can drain through the slotted openings into the interior of thetube, and filter material completely occupying the open space defined bythe flat peaks and valleys and the interconnecting walls in the area ofthe slotted openings whereby liquid draining through the slottedopenings into the interior of the tube initially passes through thefilter material, and wherein outwardly bulging portions are provided inthe interconnecting walls and the slotted openings are located in theoutwardly bulging portions.

References Cited UNITED STATES PATENTS 3,330,303 7/1967 Fochler 138-121X3,440,822 4/1969 Hegler 61-10 649,415 5/1900 Shaffer 138-98X 3,103,7899/1963 McDuff et a1. 61-11 3,190,338 6/1965 Wolfe 152-370 3,272,2539/1966 Brose 152-370 3,302,408 2/1967 Schmid 61-13 3,374,634 3/1968Fochler 61-10 JACOB SHAPIRO, Primary Examiner US. Cl. X.R.

